1. Technical Field
This invention relates to an optical transmission system for optically transmitting information from a subcenter over a plurality of optical transmission lines to a plurality of optical network units.
2. Discussion of Related Art
WO 95/05041 discloses a system for optically transmitting information from a subcenter to a plurality of optical network units via a plurality of optical transmission lines. The subcenter is connected to the optical network units by a passive optical distribution network consisting of optical transmission lines and an optical splitter. At the subcenter, a plurality of electric subcarrier signals are combined into a frequency-division multiplex signal and subsequently converted from electrical to optical form. The subcarrier signals are television signals, for example, which are destined for all optical network units, and telephone signals, each of which is destined for only one of the optical network units. For the telephone signals, unlike the television signals, only a small frequency range is reserved. If a multitude of customer locations are connected via the optical network units to the subcenter, this relatively small frequency range does not suffice to make available a sufficient number of channels for the multitude of customer locations.